title: The contribution of optical coherence tomography in neurodegenerative diseases.
abstract: OBJECTIVE
  This review investigates the contribution of optical coherence tomography (OCT) to monitoring of neurodegeneration in the anterior visual pathway of patients with neuromyelitis optica, Alzheimer's disease, and Parkinson's disease. Despite a 'normal' regular ophthalmologic examination, some patients present visual complaints, and OCT might better explain the mechanism associated to neuronal and axonal losses that contribute to this clinical condition.
  
  
  RESULTS
  The eye can be considered a 'window' to the central nervous system that can be directly accessed through OCT. Prior studies have suggested that pathologic processes in the brain are very similar to what happens in the eye in neurodegenerative diseases, and OCT has confirmed these abnormalities regarding the anterior visual pathway. It is supposed that transsynaptic neurodegeneration in lesions of the posterior visual pathway may play a role in the neurodegeneration process of the anterior visual pathway.
  
  
  CONCLUSIONS
  Retinal nerve fiber layer, retinal ganglion cells, and inner retinal layers are considered surrogate biomarkers in the progression of neurodegenerative diseases. Because OCT is able to accurately measure neuropathological ocular features, its application has increased both in neuroprotection studies and in treatment. In fact, it may prove to be a unique evaluation tool in comparison with conventional visual tests.
  (Supplementary Digital content 1, http://links.lww.com/COOP/A10).
authors.affiliation: Neuro-Ophthalmology Service, Avistar Clinica de Olhos, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Luciano M
authors.initials: LM
authors.lastname: Simao
mesh_terms: D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D019636:Neurodegenerative Diseases / Q000175:diagnosis*; D041623:Tomography, Optical Coherence / Q000379:methods*